Circuit interrupter



Jan. 26, 1954 Filed June 14, 1950 Fig.l.

6 Insulation WITNESSES: 5.42 241 R. c. VAN SICKLE ET AL CIRCUIT INTERRUPTER 4 Sheets-Sheet 1 Fig.3.

INVENTORS Roswell C.Von Sickle ondJOmesM .Curnminq,deceosed,

by Helenlicumminqfixeculrix.

Jan. 26, 1954 R. c. VAN SICKLE ET AL ,667,5 6

' CIRCUIT INTERRUPTER 4 Sheets-Sheet 3 Filed June 14, 1950 WITNESSES: INVENTORS Roswell C.Voq Sickle and JamesMCumming, ffl/fw deceased, byHelen #mmmgfixecutrix. Z ATTORNE? Patented Jan. 26, 1954 CIRCUIT INTERRUPTER Roswell C. Van Sickle, Wilkinsburg, Pa., and

JamesM. Cumming, deceased, late of Monroeville, Ba, by Helen J. Cumming, executrix, Monroevllle, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application June 14, 1950, Seiial No. 167,988

11 Claims. (01.200-150) This invention relates to circuit interrupters, and, more particularly, to are-extinguishing structures. therefor.

A general object of our invention is to provide an improved circuit interrupter which will more rapidly and efiective'l'y interrupt the circuit therethrough than has heretofore been attained.

Another object is to provide an improved arcextinguishing structure for a liquid-break type of circuit interrupter in which the contact structure is more easily adjusted, and in which maintenance and servicing are more readily brought about. I

A more specific object is to provide an improved movable contact assembly for a circuit interrupter of the type specified in the immediately preceding paragraph.

sun another object is to provide an improved circuit interrupter in which the movable contact assembly is such that improved operation is obtained, and the movable contact assembly may be completely removed from the interrupter for inspecuon purposes more easily than has heretofore been obtained. n

, Still a further object is to provide. an improved liquid-driving piston for a circuit interr'upte'r of the foregoing type for aiding in the extinction of low currents.

Another object is to'pr'ovide an improved casmg construction for a circuit interrupter in which the casing may be removed while permitting the skeleton supporting framework to remain in place so that the interior of the interrupter may be easily viewed, and contact adjustment and inspection may more readily be brought about.

A further object is to provide an improved actuating mechanism fora, circuit interrupter of the foregoing typein which the speed of movement of the movable contact assembly may be considerably more than thatof the liquid-driving piston pump used for aiding in low-current interruption, and in which during high-current interruption the pumping piston may remain stationary due to the high pressuregenerated and yet the movable contact assembly may readily and rapidly move to its fully open circuit position;

A further object is to provide an improved circuit interrupter having an improved movable contact assembly in which the movable contacts are disposed angularlyabout the axis of the movable contact assembly so that the interrupting chambers for the interrupting contacts may have exhaust ports out of the casing 2 in different directions to prevent eizternal voltage breakdown.

Further objects and advantages will readily become apparent upon reading the following specification, taken in connection with the draw-- ings, in which:

Figure 1 is a side elevational view of a circuit interrupter embodying our invention;

Fig. 2 is an enlarged elevational view, partially in vertical section, of the improved circuit interrupter of our invention, the contact structure being shown in the fully open position with the circuit disconnected;

Fig. 3 is an enlarged fragmentary view, taken in vertical section, of the upper end of the ini proved arc-extinguishing assemblage of our in vention, the contact structure being shown in the fully open-circuit position;

Fig. 4 is a view similar to Fig. 3, but showing the lower end of the improved arcs-extinguishing assemblage, the contact structure being, of course, similarly shown in the open-circuit posi tion;

Fig. 5 is a plan view of our improved movable contact assemblage;

Fig. 6 is a side elevational view of our improved movable contact assemblage;

Fig. 7 is a sectional view taken along the line VII-VII of Fig. 4;

Fig. 8 is a sectional view taken along the line VIII-VIII of Fig. 4, looking in the direction of the arrows; and

Fig. 9 is a vertical sectional view taken along the line of Fig. 4, looking in the direcs tion of the arrows.

Referring to the drawings, and more particularly to Fig. 1 thereof, the referencenurneral l designates a suitable base upon which is supported upstanding angle members 2, braced by diagonally extending angle iron supports 3. The up-standing support, generally designated by the reference character 4, supports at its upper end a circuit interrupter 5 comprising a high voltage bushing 6, preferably of the cond nser type, e2 tending into casing means I. A line terminal 8 is disposed at the upper end of the bushing 6-, and a second line terminal 9 is disposed at the lower end of the casingmeans I. A

Referring to Fig. 2, which more clearly shows the internal construction of the circuit inter rupter 5, it will be noted that the interrupter 5 is supported by the support 4, intermediate the ends thereof, at a metallic housing support I 0, the latter being secured, asby bolts, not shown, to the upper angle support I I of the support 4-.

and the movable disconnect contact 25.

' As illustrated, the terminal bushing 6 extends within the casing means 1 and has depending from the lower end thereof an arc-extinguishing means, or assemblage, generally designated by the reference character I2. The assemblage [2 is clamped, as at [3, to the terminal stud l4 extending internally through the bushing 6. An insulating operating rod I5 is movable substantially longitudinally externally of the assemblage l2, being pivoted at its upper end, as at l6, to a crank arm H, the latter being fixedly secured to a shaft IS. The shaft [8 extends externally of the housing support l0, and may be actuated by a crank arm 19 connected to any suitable mechanism.

The lower end of the operating rod I5 is pivotally connected, as at 20, to a contact-actuating member 2|. The actuating member 2| slides vertically in a slotted raceway 22 formed in an upstanding support bracket 23, the latter being supported by bolts 24 to the lower end of the casing means I, as shown.

The contact-actuating member 2! has connected thereto a lower movable disconnect contact 25, which is shown in the fully open disconnect position in Fig. 2. During the closing operation, the crank arm I9 is rotated clockwise around the shaft 18 to move the operating rod 15 upwardly to thereby cause upward closing movement of the contact-actuating member 21 The upward motion of the movable disconnect contact 25 into the opening 26 (Fig. 4) of the lower shield 21 of the assemblage 12 causes engagement between the upper tip portion 28 of the movable disconnect contact 25 and a relatively stationary disconnect contact member 25, shown more clearly in Figs. 4 and 9.

Certain features of the supporting framework 4 and mounting features for the interrupter 5, together with the operating arrangement therefor are set forth and claimed in the United States Patent 2,479,381, issued August 16, 1949, to Leon R. Ludwig and Benjamin P. Baker and assigned to the assignee of the present invention.

The casing means 1 includes a cylindricallyshaped porcelain member 30, under compression, which surrounds an internally disposed insulating cylinder 3| under tension. The cylinder 3! is clamped at its upper and lower ends to ringshaped support members 32, 33. The upper ringshaped support member 32 is secured by suitable means, not shown, to the grounded metallic hous ing support I0. The lower end ring-shaped su port member 33 is bolted, as at 34, to a plurality of steel spring rings 35, which support at the outer periphery thereof a cylindrical member 36, the upperend of which supports through a suitable gasket 31, the lower end of the porcelain casing 30. Thus, the porcelain casing 39 is, as mentioned, under compression, and the insulating cylindrical member 3| is under tension. A suitable arc-extinguishing liquid, such as circuit breaker oil 38, fills the casing l to the level 39.

Referring more particularly to Figs. 3, 4, '7, 8 and 9, which more clearly show the internal construction of the arc-extinguishing assemblage 12, it will be noted that the upper clamp I3 is suitably secured by means not shown to an upper support plate 40 (Fig. 3). A plurality of bolts 4|, positioned around the periphery of the plate 4! extends through apertures 42 provided at the upper end of an insulating tubular casing 44. Circular members 43 with transverse tapped holes therein serve as nuts for the bolts 4|, thereby holding the casing 44 rigidly in place. Casing 44 extends along the entire length of the extinguishing assemblage l2, and forms a plurality of interconnected pressure chambers 45.

Movable internally within the arc-extinguishing assemblage i2, and axially thereof, is a movable contact assemblage, generally designated by the reference character 46. The contact assemblage 45 resiliently carries therewith a plurality, in this instance three, bridging contact assemblages, generally designated by the reference numeral 41, and each comprising a movable pressure-generating contact 48a, 48b, or 48c and a movable interrupting contact 49a, 491), or 490.

The movable interrupting contacts 49a, 49b and 490 make abutting contacting engagement with stationary interrupting contacts 50a, 50b and 500. The stationary contacts 50a, 50b and 500 are adjustably secured in place having their upper ends threaded, as at 5|. A locking nut 52 is tightened after the adjustment has been made.

The movable pressure-generating contacts 48a, 48b and 480 engage in abutting engagement, a plurality of stationary pressure-generating contacts 53a, 53b and 530, which are also adjustable, having their upper ends 54 threaded, and clam ing nuts 55 being tightened after the adjustment is once made.

It will be observed that the actuating rod 56 (Fig. 6) for the movable contact assemblage 48 is composed of insulating material, and has the bridging contact assemblages 41 resiliently supported thereon by compression springs '53. The compression springs 51 have their lower seats upon flanges 58 secured to and movable with the actuating rod 56. The upper ends of the compression springs 51 seat upon the bridging portions 59 of the bridging contact assemblages 41. The upward motion of the bridging portions 59 is limited by enlarged portions or sleeves Bil surrounding the actuating rod 56. The lower end 6| of the movable contact assemblage 46 is formed of conducting material, the purpose for which will appear hereinafter.

In the closed circuit position of the interrupter, the electrical circuit therethrough includes line terminal 8, terminal stud I 4, conducting clamp l3, support plate 40, upper stationary interrupting contact 50a (Fig. 3), upper movable interrupting contact 48a, bridging portion 59, movable pressure-generating contacts 48a, upper stationary pressure-generating contact (not shown), suitable contact strap means (not shown) to middle stationary interrupting contact (not shown). The circuit then extends through middle movable interrupting contact 49b, through the conducting bridge 59 to the middle movable pressure-generating contact 48b, through middle stationary pressure-generating contact 53b (Fig. 3), through conducting strap 81 to the lower stationary interrupting contact 500, to lower movable interrupting contact 490, through lower conducting bridge 53 to lower movable pressure-generating contact 48c.- The circuit then extends through lower stationary pressure-generating contact 530 and through a conducting strap 62 to lower conducting plate 63.

The circuit then extends through a casting member 64, through conducting spring fingers 65 to the conducting portion 6| of the movable contact assemblage 43. The circuit then extends through a flexibleconducting strap connection 66 to the relatively stationary disconnect contact mem'ber'29, The circuit then proceeds through the; movable. disconnect contact: 25;. throughi the contact actuatingr member: 22h, through thei s-up:- port: bracket; 23; and: through: thecasting: 6215 to lower; plate: 6-8,. to. the. lower line terminal: 9: of the interrupter: 1

To:facil itate the. interruption: of thaintemzupts ing: arcs; 69. which. are drawn during; the; opening operation, we: provide: suitable: interrupting arc;- extinguishing units, generally! designated by: the reference character 1:0: Each. arc-extinguishin unit 18' is formed; out. of. a. plurality: of, suitable? configured insulating; plates heldr in contiguous relationship: by threeinsulating tie; rods M: and insulating spacer sleeves T2; Surrounding. the three insulating tie; rods III at; the; upper.- ends thereof are threecompression springs which serve; to maintain the; several; insulating plates under: desired compressive; force so: that they will maintain. their contiguousv relationship.

The? arc-extinguishing units HI; WillaIlOVW be; described. Referringparticul'arly"to; Riga/i and, 7 which more clearly illustrate the lower; interrupt:- ing; arc-extinguishing unit 1-0;. it, will: be; noted that the: upper'plate of the; unit, 10 is designated by the: reference character M. This plate '14 has; a singleaperture formed therein.v to accommodate the lower stationary interrupting contact, 500, as shown in Fig. 4. The; plate 14 also. has two apertures; 1'6: formed. therein (Fig; 7) to accommodate the insulating tie rods Hi. Immediately below the insulating plate; 10: isan insulating vent. plate TL, having a configuration more clearly shown by the dotted, linesin Fig. 7 The; vent plate 11 has a sir-t out, portion '18-. re,- moved therefrom to form a. vent passage 19 which. leads out. of the casing; 413 through suit..- able openings 81% formed therein.

Immediately below the vent, plate H is an insulating orifice plate designated by the reference character 8&1. The orifice plate 81- is similar in configuration. to the insulating plate M previously described, except that it is less. thick than the plate [4.

Immediately below the insulating orifice; plate BI: is an insulating inlet, plate 352 which has a configuration more clearlyshown in- Eig-i '1. It will be observed that the insulating inlet plate 82 has the apertures is (as do, all the other plates) as well as a cutout portion &3 (Fig. 7') whichforms an inlet passage as.

Immediately below the inlet plate 82 is a, sea ond orifice plate st. Then tollows a second vent plate 11, orifice plate 2H, inlet plate 8-2, orifice plate 8i, and a lower vent plate ll. Below the vent plate H is an insulating plate 85.: which extends across the casing 44 andhas a. diamondshaped opening 86 formed therein, the purpose for which will appear more clearly hereinafter.

The particular multiflow interrupting structure 10 is more fully described, and the theoretical reasons for its performance are more hill-y set out in United States Patent 2,467,760, issued April 19., 1949, to Leon R. Ludwig, Benjamin F. Baker and Winthrop M. Leeds and assigned to the assignee of the instant. application.

To assist in the interruption of low amperag currents, we provide suitable piston means, generally designated by the reference character 89, and including a piston Bil, movable within a piston chamber 9!. The pistontfihas a plurality of apertures 92 provided therein. A ring-shaped valve plate 93 controls the passage of liquid. in this instance oil, through the apertures a2, the valvev ring 93 being supported by bolts 94 to the piston 90, as shown more clearly in Figs. 4 and. 9..

6 The Wis: downwardl -in a w rk.- ing direction by a compression spring Qlirwhich eats: at ts; upper nd. aga nst he upper w it: oi: a. snitabln qfl tfiggured casting, m b r 912 1 castin member: 1 s cured; y o s 9 to the: m talli p aic-v 63? o the assemblage l;2;..

It will b Qbserved-thahthe casting memb r has: one: or m re iqu d: onduits 9 formsd in the; side walls; thcreot (Fig. 4) which connect hydraulically he ower. work ng: fa e;- moi o the p st n: 9.0.; t ro gh a passa e N3 o h owe most p s ur chamber 45; Q th s emb a I 2 As; previon ltr cribed, moth-rec pr r chambe s 45; area-. 11. nterconnect d: so t at there is a free. pass ge; of: oil: rom; the pi t ham ber. M. hrough conduits 99, pass ges "l -t. to 1 of, the; pressure chamhezzs- 45F throughout the assembla e 1.2;.

compression 95t seats at its lower enslupon; a shoulder: I192 termed ona downwar s" xtendin y indr cal xte s n I16 o the piston. member; 9.05, as; ShQwn; more clearly in 4 and Q. The, the piston member 9,3: is biaseo downwardl f n: a ln dl dr ng ir c io pring 951..

Rete-iirmg to Fig. 9,, it will? beobserved that the lower cylindrical extension I03, ot the piston 89 hasa p ir: of: slots: lm tormesi ther in v the lower end thereof: through e en s a sin N15. The pin, we extends; through; the relatively stationary disconnecting contact, 29. and also through a pair: of lovers M15, pivotally connected at heir righ hanoa ds.- to a sta nary pivo The s ation ry pivo s mou on a stationary Support bracket m8; bolted, as at I09,

o cas mam mbcr l Ht Brei rably a pl I i I is; welded to? the lower sides. of the two. lovers the to. ive them. adsii ional rigidity.

A pin H2 extends through the. left-hand ends or the lev rs m6 and. also extends through the lower ends; of a p le" f H T e pp r ends of; the. links Its have a. pin its extendin therethrongh, thcpin H4 also: extending through a pair of lovers; H5, which have, their left-hand.

' ends secured by a pivotal connection at HB to the lower end of a. support: bracket NW. The bracket H1 is. secured by bolts l: 1'8 to the castneg member I- M A pin H9= extendsthroughthe right-hand levers I #5 and rides. in a slot l Zll disposed in the lower end oi the actuating rod 56 as shown more clearly in Fig; 6

Integrally formed with the relatively stationary disconnect member 29 are a pair of pins $21 which ride in the slots HM ofcylindri'eal extension H13 for the purpose of guiding the relatively stationary disconnect member 29. It will be noted that; the relatively stationary disconnect member 29 has an open tapered recess i2 2 formed therein to accommodate the upper tip portion 28 of the movable disconnect contact d 2.5. The. dep nding cylinder I03. ma have additional lot E 3 th r in to accommodate movement of the leverage mechanism.

The charging notion of the piston 98 will now be d scribed- Upw r i c s n motion of the movable disconnect contac r d causes the. tip 28 thereof to ent r the rece I2 0i r 1 tivelr sta ionary dis onne t Con a t. m m er 9 to cause upward. closing m tion o h same. Since the pin. 05 is secured. by a pres lit to the contact. carrier 23., it moves pwardly toge her with the conta t carrie 29, and, movab e di connect contact 25 to thereby rotate the. le ers I06 in a clockwise direction about the stationary pivot I01.

The clockwise rotation of the levers I about the stationary pivot I01 causes corresponding upward motion of the links H3 and hence counterclockwise closing motion of the levers II5 about their stationary pivot IIE. This causes upward motion of the pin H9 and hence upward motion of the actuating rod 59 and hence the movable contact assemblage 45. Also, since the pin I05 moves up, by its engagement with the upper ends of the slots I04 of the cylindrical extension I03 of the piston member 90, it causes upward closing charging movement of the piston member 90 in opposition to the biasing action exerted by the compression spring 95. Because of the leverage in the mechanism I38 upward travel of rod 56 occurs at a greater rate of speed than upward travel of relatively stationary disconnect contact member 29 and piston 90. Piston 90, of course travels with relatively stationary disconnect contact 29. During this closing charging movement of the piston 90, the valve ring 93 remains open to permit liquid to flow out of the region I23, through the apertures 92 and into the region I24 within the piston chamber 9|.

It will be observed that we have provided a second compression spring I25 biasing the actuating rod 56 downwardly. The upper end of the compression spring I25 seats against the upper wall 96, and the lower end of the compression spring I25 seats against a flange I26 integrally formed with the conducting part SI of the actuating rod 55. During the upward closing motion of the actuating rod 56, as previously described, the compression spring I25 is compressed well as the compression spring 95 which biases the piston 95 downwardly.

To halt the downward opening motion of the actuating rod 56, we have provided a pair of bosses I21 integrally formed with the flange I25 which strike a piston I28 of a dashpot means, generally designated by the reference character I29. The dashpot means I29 includes a dashpot piston I23 which moves within a dashpot piston chamber I30 having a plurality of apertures I3! provided therein. Also a return compression spring I32 is provided to move the dashpot piston I29 upwardly above the apertures I3I during the closing operation.

It will be observed that the cylindrical extension I63 has a pair of slots I33 formed therein to accommodate motion of the bosses I21 without their interfering in any manner with motion of the cylindrical extension I03 and hence the piston member 90.

It will be observed that the casting member iii} not only provides the dashpot piston chamber I30, but also has one or more upstanding wall portions I34 (Figs. 4 and 9) which permit the upper end thereof to be bolted by bolts I95 to a cylindrical casting member I36 and also to the lower end of the casting member 91, as shown mere clearly in Fig. 4.

The operation of our improved interrupter will now be described. In the closed circuit position of the interrupter the electrical circuit extends therethrough in the manner previously described, and the disconnect member 25 maintains the contact carrier 29 upwardly in its closed position, not shown, maintaining thereby the actuating rod 56and the piston member 90 in their upward closed position. Contact is made between W all the movable contacts and all the stationary 8 contacts with the compression springs 51 providing the desired contact pressure.

To effect an opening operation of the interrupter suitable mechanism, not disclosed, but responsive to either manual operation or to the existence of overload conditions existing in the circuit controlled by the interrupter is operative to cause counterclockwise opening rotative motion of the crank arm I9. This causes down-- ward opening motion of the operating rod I5 and hence movable disconnect contact rod 25. The downward motion of the movable disconnect contact rod 25 permits the contact carrier 29 to be forced downwardly by the linkage previously described in response to downward biasing action of the accelerating compression spring I25. The downward motion of the actuating rod 56 and hence the contact assemblage 46 opens the several pairs of pressure-generating and interrupting contacts simultaneously to establish hereby simultaneously three pressure-generating arcs I31 and three interrupting arcs 69.

Although Fig. 4 indicates a fully open circuit position of the interrupter 5, nevertheless for purposes of clarity we have drawn in the pressure and interrupting arcs 69, I31. The interrupting arcs 59 are all drawn within the three interrupting arc-extinguishing units 10. The three pressure-generating arcs I31 are drawn within the interconnected pressure chambers 45. Consequently, the three pressure-generating arcs i31 react upon the oil, which completely fills the casing 44 to form pressure within the pressure chambers 45. As a result, oil under pressure is forced from the three pressure chambers 45 through the several inlet passages 84 associated with the three interrupting units 10. The oil entering the inlet passages 84 strikes the interrupting arcs 59, flows longitudinally through the orifices 15 and out of the assemblage I2 through the several vent passages 19 and openings 89. Interruption of the interrupting arcs 69 soon occurs and the circuit is consequently interrupted.

If the pressure generated within the pressure chambers 45 is low because of the low amperage current being interrupted, the piston will move down as a result of compression spring 95, closing the valve ring 93 over the apertures 92 and force oil from the region I24 through the conduits 99 through passage means IM and into the interconnected pressure chambers 45, whence the oil can flow through the interrupting units 10 in the manner previously described. However, if the pressure generated within the pressure chambers 45 is high, as a result of high pressure being established at the pressure-generating arcs I91 in response to high current interruption, then the high pressure thus generated may stall the piston 90 preventing it from moving downward- 1y. It will only move downwardly following subsidence of the pressure within the pressure chambers 45 following circuit interruption, and in so doing will send a flushing flow of liquid through the pressure chambers 45 and through the three interrupting units 10 to wash carbonized oil out of the units 10 through the exhaust passages 19.

It is to be noted, however, that whether the piston 90 moves downwardly or not, dependent upon the pressure conditions within the pressure chambers 45, nevertheless, the contact assemblage 46 will always move downwardly unhindered by any motion whatsoever of the piston member 90. This follows because of the provision of the slots I04 in the cylindrical extension I03 rnitting ready inspection to be had of the contact structure and also contact operation.

2. A circuit interrupter of the liquid break type, a movable disconnect contact member, a relatively stationary disconnect contact carrier, a

movable contact assemblage, one or more movable contacts carried by the contact assemblage, movable piston means, the movable disconnect contact member striking the relatively stationary disconnect contact carrier during the closing operation of the interrupter, means interconnecting the piston means with the relatively sta- "tionary disconnect contact carrier, and means interconnecting the movable contact assemblage with the relatively stationary disconnect contact carrier so that an accelerated closing motion of the assemblage relative to the disconnect contact carrier results.

3. A circuit interrupter of the liquid break type including an arc extinguishing assemblage, means supporting the arc extinguishing assernblage adjacent one end thereof, a skeleton framework extending along the assemblage, the assemblage including a plurality of arc extinguishing units disposed in spaced relation, one or more pressure chambers disposed within the arc extinguishing assemblage, contact structure supported by said skeleton framework, and a removable casing forming a portion of the wall of said one or more pressure chambers and removable from the assemblage from the opposite end thereof without disturbing the arc extinguishing units so that contact operation may be visually observed.

4. A circuit interrupter of the liquid break' type, a movable disconnect contact member, a relatively stationary disconnect contact carrier, a movable contact assemblage, one or more movable contacts carried by the contact assemblage,

.movable piston means, the movable disconnect I contact member striking the relatively stationary disconnect contact carrier during the closmeans, means interconnecting the other end of the first said lever means to an intermediate point of the said second lever means, and means carried by the movable contact carrier for charging the piston means.

5. A circuit interrupter of the liquid break type, a movable disconnect contact member, a relatively stationary disconnect contact carrier, a movable contact assemblage, one or more movable contacts carried by the contact assemblage, movable piston means, the movable disconnect contact member striking the relatively stationary disconnect contact carrier during the closing operation of the interrupter, lever means pivoted adjacent one end thereof to a substantially stationary pivot, the contact carrier being pivoted to an intermediate point of the said lever means,

'fsecond lever means pivoted adjacent one end thereof to a substantially stationary pivot, the movable contact assemblage being pivoted adjacent the other end of the said second lever means, means interconnecting the other end of the first said lever means to an intermediate point of the said second lever means, means carried by the movable contact carrier for charging the piston means, and means permitting the piston means to remain stationary during the opening operation of the interrupter due to high gas pressure, when the contact carrier and contact assemblage move to the open circuit position.

6. A circuit interrupter including a casing, a movable contact assemblage movable within the casing, the movable contact assemblage having an actuating rod and a plurality of bridging contact assemblages movable therewith, each bridging contact assemblage including a bridging portion, each bridging portion including a movable pressure-generating contact at one end thereof and a movable interrupting contact disposed at the other end thereof, a relatively stationary arcextinguishing unit for each movable interrupting contact to extinguish the are drawn thereat, each arc-extinguishing unit being disposed offcenter within the casing, and each bridging portion being angularly displaced about the actuating rod with respect to the adjacent bridging portion to clear the adjacent arc extinguishing unit.

7. A circuit interrupter including a movable disconnect contact member, a relatively stationary disconnect contact carrier, a movable contact assemblage, one or more movable contacts carried by the contact assemblage the movable disconnect contact member striking the relatively stationary disconnect contact carrier during the closing operation of the interrupter, lever means pivoted adjacent one end thereof to a substantially stationary pivot, the contact carrier being pivoted to an intermediate point of the said lever means, second lever means pivoted adjacent one end thereof to a substantially stationary pivot, the movable contact assemblage being pivoted adjacent the other end of the said second lever means, and means interconnecting the other end of the first said lever means to an intermediate point of the said second lever means to effect the actuating thereof.

8. A circuit interrupter including a casingya movable contact assemblage movable within the casing, the movable contact assemblage having an actuating rod and a plurality of bridging contact assemblages movable therewith, each bridging contact assemblage including a bridging portion, each bridging portion including a movable pressure-generating contact at one end thereof and a movable interrupting contact disposed at the other end thereof, a relatively stationary arcextinguishing unit for each movable interrupting contact to extinguish the arc drawn thereat, each arc-extinguishing unit being disposed off-center Within the casing, the movable interrupting contact being of greater axial length than the movable pressure-generating contact of each bridging contact assemblage so as to enter the are extinguishing unit associated therewith, and each bridging portion being angularly displaced about the actuating rod with respect to the adjacent bridging portion to clear the adjacent arc extinguishing unit.

9. A circuit interrupter including a movable contact assemblage, the movable contact assemblage including an actuating rod and a plurality of centrally located bridging contact assemblages movable therewith and disposed along the axis thereof in spaced relation, each bridging contact assemblage including a bridging portion and a pair of movable contacts disposed adjacent the opposite ends of the bridging portion, one 01' the two movable contacts of each pair being of greater axial length than the other movable contact, and each movable contact of greater axial length being angularly displaced about the actuating rod with respect to each adjacent movable contact of greater axial length.

10. A circuit interrupter including a movable contact assemblage, the movable contact assemblage including an actuating rod and a plurality of centrally located bridging contact assemblages movable therewith and disposed along the axis thereof in spaced relation, each bridging contact assemblage including a bridging portion and a pair of movable contacts disposed adjacent the opposite ends of the bridging portion, and the bridging portion of one bridging contact assemblage being angularly displaced about the actuating rod with respect to the bridging portion of the immediately adjacent bridging contact assemblage.

11. A circuit interrupter including a movable contact assemblage, the movable contact assemblage including an actuating rod and a plurality of bridging contact assemblages movable therewith, each bridging contact assemblage including a bridging portion and a pair of movable contacts disposed adjacent the opposite ends of the bridging portion, one of the two movable contacts of each pair being of greater axial length than the other movable contact, a pair of relatively stationary contacts cooperable with each pair of movable contacts to establish a pair of serially related arcs, the arcs along the assemblage being established in staggered positions, and the bridging portion of one bridging contact assemblage being angularly displaced about the actuating rod with respect to the bridging portion of the immediately adjacent bridging contact assemblage.

ROSWELL C. VAN SICKLE.

HELEN J. CUMMING, Emecutrisc of the estate of James M. Cumming,

deceased.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 708,006 Ball Sept. 2, 1902 1,350,924 Eaton Aug. 24, 1920 2,138,382 Leeds et a1 Nov. 29, 1938 2,164,175 Frank June 27, 1939 2,228,432 Baker et a1 Jan. 14, 1941 2,460,450 Cumming Feb. 1, 1949 2,463,029 Fry Mar. 1, 1949 2,477,781 Baker et al Aug. 2, 1949 2,518,195 Skeats Aug. 8, 1950 2,522,994 Coggeshall Sept. 19, 1950 2,539,175 Balentine Jan. 23, 1951 

